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A Bench Top Study of the Optimization of LVAD Cannula Implantation to Reduce Risk of Cerebral Embolism
Title
A Bench Top Study of the Optimization of LVAD Cannula Implantation to Reduce Risk of Cerebral Embolism.
Creator
Clark, William, Kassab, Alain, Divo, Eduardo, Ilie, Marcel, University of Central Florida
Abstract / Description
Physical bench top experiments are performed to validate and complement ongoing computational fluid dynamics (CFD) analyses of ventricular assist device (VAD) circulation. VADs are used in patients whose hearts do not function to their maximum potential due advanced stages of heart disease and, consequently, are unable to adequately supply blood to the systemic circulation. VADs are commonly utilized as a bridge-to-transplantation, meaning that they are implanted in patients while waiting for...
Show morePhysical bench top experiments are performed to validate and complement ongoing computational fluid dynamics (CFD) analyses of ventricular assist device (VAD) circulation. VADs are used in patients whose hearts do not function to their maximum potential due advanced stages of heart disease and, consequently, are unable to adequately supply blood to the systemic circulation. VADs are commonly utilized as a bridge-to-transplantation, meaning that they are implanted in patients while waiting for a heart transplant. In such cases of long term utilization of VADs, it has been reported in the literatures that thrombo-embolic cerebral events occur in 14-47% of patients over the period of 6 to 12 months. This is a result of thrombus forming despite the use of anticoagulants and advances in VAD design. Accepting current rates of thrombo-embolisms, the main objective of the project is to identify and propose an optimal surgical cannula implantation orientation aimed at reducing the rate of thrombi reaching the carotid and vertebral arteries and thus reduce the morbidity and mortality rate associated with the long term use of VADs to patients suffering from advanced heart failure. The main focus of the experiment is on the physical aspect using a synthetic anatomically correct model constructed by rapid prototyping of the human aortic arch and surrounding vessels. Three VAD cannula implantation configurations are studied with and without bypass to the left carotid artery or to the Innominate artery with ligation of the branch vessel at its root. A mixture of water and glycerin serves to match blood viscosity measured with a rotating cone-plate viscometer. The Reynolds number in the ascending aorta is matched in the flow model. A closed loop mock circulatory system is then realized. In order to match the Reynolds number in the ascending aorta and LVAD cannula with that of the CFD model, a volumetric flow rate of 2.7 liters per minute is supplied through the synthetic VAD cannula and 0.9 liter per minute is supplied to the ascending aorta. Flow rates are measured using rotary flow meters and a pressure sensor is used to ensure a mean operating pressure of 100 mmHg is maintained. Synthetic acrylic blood clots are injected at the inlet of the VAD cannula and they are captured and counted at the vertebral and carotid arteries. The sizes of the thrombi simulated are 2, 3.5 and 5 mm which are typical of the range of diameters encountered in practice. Nearly 300 particles are released over 5 separate runs for each diameter, and overall embolization rates as well as individual embolization rates are evaluated along with associated confidence levels. The experimental results show consistency between CFD and experiment. Means comparison of thromboembolization rates predicted by CFD and bench-top results using a Z-score statistic with a 95% confidence level results in 22 of 24 cases being statistically equal. This study provides confidence in the predictive capabilities of the bench-top model as a methodology that can be utilized in upcoming studies utilizing patient-specific aortic bed model.
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Date Issued
2012
Identifier
CFE0004365, ucf:49412
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004365
The Impact of Access to Books on the Reading Motivation and Achievement of Urban Elementary Students
Title
The Impact of Access to Books on the Reading Motivation and Achievement of Urban Elementary Students.
Creator
Trimble Spalding, Lee-Anne, Hynes, Michael, Kelley, Michelle, Hoffman, Bobby, Clark, Margaret, Williams, Robert, University of Central Florida
Abstract / Description
The focus of this research was to study the association that reading motivation and reading achievement have with increased access to books provided by the non-profit program Book Trust, could have on urban elementary students, specifically second graders being educated in a large school district in Central Florida. Teacher data collection sheets, the Motivation to Read Profile (MRP): Reading Survey and the Florida Assessment for Instruction in Reading (FAIR) were used to measure the...
Show moreThe focus of this research was to study the association that reading motivation and reading achievement have with increased access to books provided by the non-profit program Book Trust, could have on urban elementary students, specifically second graders being educated in a large school district in Central Florida. Teacher data collection sheets, the Motivation to Read Profile (MRP): Reading Survey and the Florida Assessment for Instruction in Reading (FAIR) were used to measure the aforementioned associations. Findings revealed that increased access to books in these elementary schools did not have a statistically significant impact on reading motivation or reading achievement scores. In addition, teachers' demographic data, such as age, number of years teaching or highest degree held, did not impact their student reading achievement.
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Date Issued
2012
Identifier
CFE0004611, ucf:49933
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004611
The atom bomb and you
Title
The atom bomb and you.
Creator
Clark, Joseph, Weinstone, William
Date Issued
1951
Identifier
2683674, CFDT2683674, ucf:5111
Format
Document (PDF)
PURL
http://purl.flvc.org/FCLA/DT/2683674
The Relationship of Computer Science Immersion in Elementary Schools to Achievement of High Poverty Students
Title
The Relationship of Computer Science Immersion in Elementary Schools to Achievement of High Poverty Students.
Creator
Erickson, Keith, Taylor, Rosemarye, Ceballos, Marjorie, Gordon, William, Clark, M. H., University of Central Florida
Abstract / Description
The purpose of this study was to determine if a relationship existed between the implementation of a computer science immersive learning experience and achievement on the Florida Standards Assessment (FSA) English Language Arts (ELA) or the FSA Mathematics. Two research questions, each with two sub-questions, guided the research of the study. The sub-questions addressed historically underrepresented groups in computer science. These subgroups included African Americans, Hispanics, Mixed Race...
Show moreThe purpose of this study was to determine if a relationship existed between the implementation of a computer science immersive learning experience and achievement on the Florida Standards Assessment (FSA) English Language Arts (ELA) or the FSA Mathematics. Two research questions, each with two sub-questions, guided the research of the study. The sub-questions addressed historically underrepresented groups in computer science. These subgroups included African Americans, Hispanics, Mixed Race individuals, and females. Research Question 1 analyzed the relationship between the implementation of the computer science immersive learning experience when a cohort control group design was used. Research Question 2 determined if a relationship existed when the treatment schools were compared to demographically similar schools that did not receive the treatment of computer science immersion. A two-way analysis of variances (ANOVA) was run for each of the research questions with the subgroups of students used as moderators for the treatment. Statistical significance was found for the following groups; fourth grade ELA Hispanic cohort, fourth grade Hispanic mathematics cohort, third grade ELA cohort, third grade mathematics cohort, the ELA treatment group, and the mathematics treatment group. Statistically significant findings showed negative, positive, and neutral effects on the treatment groups. These findings provide implications for the implementation of computer science immersion in other elementary schools with similar student demographic variables. Further investigation is needed to determine other potential impacts on student achievement over time.
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Date Issued
2019
Identifier
CFE0007627, ucf:52559
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007627